I believe it is mainly @uckelman that is focused on version 4 of Vassal - there’s still some development being done on version 3 - not least by @rlament and @marktb1961 . Joel is, however, to some extend, the bottleneck for new developments because he’s the one doing the final merging and releases.
True, but that requires that you edit the module - which is not something all users are comfortable doing. The above mentioned PR fixes the problem at the “source”, meaning all charts will have zoom capability without any module modifications.
One could also create a custom class (see Creating Custom Classes) that overrides the default VASSAL.module.build.widget.Chart element and add that to modules. However, it would again require modifications to the modules.
Yours,
Christian